Process for producing a composite component

ABSTRACT

The invention relates to a process for producing a composite component from a plastic structure ( 1, 25, 31, 37 ) and a metal body ( 4, 25, 35, 40 ) by bringing together joining tools ( 11, 13 ). Plastic structure ( 1, 25, 31, 37 ) and metal body ( 4, 25, 35, 40 ) are joined by penetration, which takes place when contact surfaces ( 12, 14 ) of the joining tools ( 11, 13 ) are brought together, of tamped edges into the plastic structure ( 1, 25, 31, 37 ), in such a manner that a permanent, positive and non-positive connection ( 34 ) is formed.

The invention relates to a composite component and to a process for itsproduction, in particular to a positively and non-positively lockingplastic/metal connection, which is formed on plastic/metal compositecomponents, and to a joining process.

EP-A 0 370 342 relates to a lightweight construction element. It has adish-shaped base body, the interior of which has reinforcing ribs whichare fixedly connected to the base body. The reinforcing ribs comprisemolded-on plastic, and are connected to the base body at discreteconnection points via apertures in the base body through which theplastic extends, then spreading over the surfaces of the apertures. Thisprocess is very complex and susceptible to wear. It requires a highlevel of outlay on tool maintenance. A high level of scrap is ofteninevitable. Moreover, for each new model variant or change, a new,usually complicated injection mold is required, making the process evenmore expensive. Consequently, series production often entails riskswhich are impossible to calculate.

The as yet unpublished European patent application reference No.00119476.0 describes further metal/plastic joining techniques. These areintended to lead to a lower level of product scrap. By way of example,the partial or full-surface adhesive bonding of metal and plastic in thecontact regions, the subsequent formation of plastic rivets by means ofpartial fusion in the apertures of the metal sheet, connection by screwsor latching hooks and joining by flanging of tabs on the metal sheet orat the edges or apertures of the plastic structure are disclosed.However, these connecting techniques either require the use of furthermaterials, e.g. adhesives or screws, or of additional process steps.

Finally, a further process for producing a composite component, asdescribed for example in the as yet unpublished German patentapplication reference No. 100 14 332.6, can be used to produce acomponent of this type which comprises a hollow profiled section basebody. The hollow profiled section base body has the cross section of ahollow profiled section which can be produced using the internalhigh-pressure forming process. At least one plastic element is fixedlyjoined to the hollow profiled section base body. The plastic element isinjection-molded onto the hollow profiled section base body and isconnected to the hollow profiled section base body at discreteconnection points, by partially or completely encapsulating the hollowprofiled section base body with the plastic which has been molded on forthe plastic element at the connection points.

Plastic-metal composite components, which are also known as hybrids orhybrid components, which have been produced using the processes whichhave been briefly outlined above are used in suitable form in motorvehicles. The hybrid components have a shell-like base body or a hollowprofiled section made from metal and a plastic structure which isfixedly connected thereto. The metallic base body imparts the basicrigidity and strength to the composite component. The plastic structureserves firstly to further increase the strength and rigidity andsecondly to allow functional integration in the context of formingsystems and modules, as well as a reduction in weight. Examples ofparticularly suitable applications for hybrid components in theautomotive industry include the front end supports or front end modules,instrument-panel modules or instrument-panel stays, door functionalsupports or door modules and similar components for tailgates and reardoors.

In view of the abovementioned solutions forming part of the prior art,the invention is based on the object of providing a hybrid componentusing an economically available joining process which, while having acomparable weight, has an increased rigidity and strength and iseminently suitable for series production.

According to the invention, this object is achieved by a process forproducing a composite component from a metal component and a plasticstructure, in which the metal component, which has at least one surfacewith at least one stamped edge, and the plastic structure are placedinto joining tools, and the joining tools are brought together, so thatthe stamped edge is pressed into the plastic structure in a positivelyand non-positively locking manner under pressure.

At the joining point, a permanent positively and nonpostively lockingconnection can be achieved by pressing together plastic structure andmetal component.

Conventional presses or stamping and/or deep-drawing machines or similarhydraulically acting joining machines, which are suitable forsheet-metalworking or sheet-metal deformation, can be used for thejoining operation, i.e. to press or stamp together metal component andplastic structure. These machines are generally equipped with one ormore tools which are matched to the contour of the composite component.To avoid fractures or cracks during joining, it should be ensured thatthe metal component and the plastic structure lying opposite it beardirectly and flat against the tool at the connection point(s) or in theimmediate vicinity thereof.

To produce higher numbers, the joining machines can be equipped with oneor more tools which are accurately matched to the contours of the partsof the hybrid components, i.e. the composite components, which are to bejoined in each case, the joining force optimally being introduced insuch a manner that the metallic body bears against the tool on one sideof the tool and the oppositely located plastic body bears against thetool at the connecting points or in their immediate vicinity on theother side of the tool. The joining can be effected by bringing togetherthe joining tools either rapidly or slowly. The joining operationenables an elevation, which is designed as a stamped collar, in themetallic base body to twist or dig into the wall of the plasticcomponent, so that a positive and non-positive connection is formed. Thejoining operation means that the stamped edge or stamped collar may bedeformed even during penetration into the plastic body. The form of theprotuberance which is deformed by the joining operation may beinfluenced firstly by the setting angle and height of the undeformedprotuberance on the metallic component and secondly by the design of thejoining tool.

With the process which is proposed according to the invention, it ispossible to join together both conventional plastic structures whichare, for example, at ambient temperature and freshly molded parts whichdrop out of the mold and are still at an elevated temperature andtherefore still relatively soft, and also plastic structures which haveundergone a subsequent heat treatment, i.e. plastic structures whichhave only been raised to an elevated temperature just before the joiningoperation, to a metal component to form a connection which is able tobear high loads.

Compared to corresponding known structures, hybrid components obtainedin this way, given the same weight, have advantages in terms of theirstrength and rigidity.

The metal component, which is also referred to as a metallic body or ametallic base body, has at least one surface which has a stamped edge.This stamped edge can be formed directly during production of the metalcomponent or may be produced subsequently. It is in this case ashoulder, projection or elevation which is able to penetrate into theplastic structure when pressure is applied. Accordingly, the end of thestamped edge is preferably angular in form, i.e. may, for example, bemachined into the shape of a rectangle, triangle or trapezium in crosssection.

Suitable stamped edges can be obtained by applying them to the metalsurface retrospectively by means of known processes, such as solderingor welding. Furthermore, stamped edges of this type may be included inthe production of the metal structure. It is preferable to obtainstamped edges by working apertures into the surface of the metalcomponent using stamping or deep-drawing processes. A very wide range ofshapes of apertures are possible depending on the choice of stampingtool and are distinguished by the fact that they have a substantiallyperpendicular stamped edge which delimits the aperture from the metalsurface. A substantially perpendicular position of the stamped edge,irrespective of whether it is formed as an aperture or producedseparately or integrally, in the context of the present invention isintended to indicate that the stamped edge adopts a setting angle of 60to 120°, in particular of 70 to 110°, with respect to the metal surfaceof the metal component. When the metal surface is considered in planview, the stamped edge may take the form of a straight or wavy orangular line or may be in the shape of a rectangle, square, triangle,oval, circle or any other desired geometric figure. In addition, anyother conceivable shape is also possible, provided that it allows metalcomponent and plastic structure to be joined by being pressed together.It is also possible for two or more stamped edges of the same ordifferent shapes to be arranged on a metal surface. Within wide ranges,the thickness of the stamped edge can be selected as desired, providedthat the plastic structure is not destroyed during the pressingoperation and that a composite component is produced. The thickness ofthe stamped edge is generally in the range from 0.2 to 2 mm; thicknessesin the range from 0.4 to 1.2 mm are preferred.

The height of the stamped edge, measured from the metal surface, isgenerally sufficient if it corresponds to the thickness of the plasticstructure at the point which is to be connected. However, a permanentconnection can also be produced even with lower height, for example witha height in the region of half the thickness of the plastic structure atthe point which is to be joined. The metal component, which is alsopreferred to as a metallic body or metal body, can be made from anydesired metal or alloy. Under the joining conditions, it must have astrength which is sufficient to make it possible to produce a permanent,positively locking connection to the plastic structure via the stampededges.

The wall thickness of the plastic structure is preferably at least 1 mm,preferably 2 to 8 mm. If plastic structures with this wall thickness arejoined to metal bodies using the process proposed according to theinvention, the stamped-collar-like elevations of the metal bodypenetrate into the plastic structure, so that a permanent, positivelyand non-positively locking connection is obtained.

The apertures in the metallic bodies are preferably of circular design.However, they may also be in the form of an oval or a rectangle withrounded corners. At the edge regions, the apertures may advantageouslybe designed with elevations which are configured in the form of stampedcollars and are forced out of the metal sheet and bent upward.

Preferably, the apertures in the metallic bodies are formed ascollar-like elevations in their edge regions. Collar-like elevationsoffer the advantage of having a peripheral edge which can in particularbe of angular design, in order to achieve improved entry into theplastic. In the metallic base body, the apertures can be produced, forexample, by stamping, deformation of the edge regions of the aperturestaking place automatically during the stamping. In addition to beingstamped, the deformations in the metallic base body can also be formedby deep-drawing of the metallic bodies.

In the process which is proposed according to the invention, the heightof the elevations on the metal body may exceed the wall thickness of theplastic structure. Therefore, it is preferable to have recourse tostamped edges whose heights exceed the thickness of the plasticstructure at the connection point by 2 to 40, preferably by 5 to 25 andparticularly preferably by 10 to 20%. Since, during the joiningoperation, pressure is built up and maintained both from the rear sideof the metal component and the plastic structure, by means of metal toolwalls which are generally resistant to deformation, the projectingstamped edges, after they have penetrated through the plastic structure,are deformed at the opposite press plate, resulting in the formation ofan even better positively and non-positively locking connection to theplastic structure.

In addition to the stamped-collar-like elevations on the metal bodybeing formed with a height which exceeds the wall thickness of theplastic structure, the height of the stamped-collar-like elevations mayalso be less than or equal to the level of the wall thickness of theplastic structure which is to be joined to a metal body. In this casetoo, pressing the parts together leads to a positive and non-positiveconnection.

According to a further design variant of the idea on which the inventionis based, the deformations may be provided at a setting angle in theplane of the apertures in the metallic body, so that they projectvirtually perpendicular to the plane of the metallic body. By selectingthe setting angle of the projections with respect to the plane of themetallic workpiece in which the apertures and therefore the deformationsare produced, it is possible to significantly influence the form of theconnection point which is produced during the joining operation.Depending on the setting angle of the deformation on the metalcomponent, the deformation contour of the stamped-collar-like elevationcan be widened or narrowed in the center or at the upper region.

In a preferred configuration of the process according to the invention,the diameter range for the apertures produced in the metallic componentis in the range from 2 to 50, in particular from 2 to 12 mm.

During the production of the apertures, the peripheral edge of thedeformations which delimit the apertures becomes preferably of angulardesign, in particular of sharp-edged design, in order to allow theperipheral edge to enter the plastic structure when the parts which areto be joined and form a composite component come into contact with oneanother.

By suitably selecting the setting angle of the elevations, which areconfigured in the manner of stamped collars, on the metallic body, thecontour of the deformation which is established in the region of thejoining point between metallic body and plastic element can beinfluenced. In addition, the deformation contour which is establishedbetween metallic component and plastic structure in the region of thejoining point between the two parts of the component can be influencedby the configuration of the contact surface of the corresponding upperjoining tool which acts on the protuberance, if the stamped edge ishigher than the thickness of the plastic structure at the joining point.

In a further embodiment, two or more plastic structures are joined toform a composite component in one operation by being pressed togetherwith a metallic component which has at least one stamped edge, asdescribed above. For this purpose, the plastic structures are locatedone above the other, without play, at the joining point, so that anon-positive and positive connection is possible. The height of thestamped edge is to be set in such a manner that the end of the stampededge penetrates through the plastic structures bearing against the metalcomponent or the bearing plastic structures and at least penetrates intothe outer plastic structure bearing against the joining tool wall orpenetrates all the way through this structure, so that the stamped edgeis deformed.

Furthermore, a reinforcing ribbed structure may be molded onto theplastic structure which is connected to a metallic component to form ahybrid component using the process according to the invention.

In a further embodiment, the plastic structure has at least onedome-shaped elevation which is open at the top and the basic surface ofwhich can form a joining surface for interaction with the stamped edgeof the metal component.

A joining tool can be introduced into the dome-shaped elevations whichare open at the top, which tool, at the base of the open, dome-shapedelevations, applies the compressive force which is required in order toform a permanent, positive and non-positive connection between plasticstructure and metal body when the joining surfaces are brought together,so that the stamped-collar-like elevations of the metal body penetrateinto the plastic of the base surface of the dome-shaped elevations.

In a preferred embodiment, the plastic structure has two or moredome-shaped elevations which are open at the top and at least two ofwhich are connected to one another by a reinforcing plastic rib, theunderside of which may also bear against the metal component. Thedome-shaped elevations particularly preferably form intersection pointsof rib-shaped plastic structures. These plastic structures can readilybe produced by means of conventional injection-molding processes. Incomposite components, particular strengths and rigidities are achievedif every or almost every base plate of a dome-shaped elevation isconnected to the metal component via a stamped edge.

Furthermore, the open, dome-shaped elevations can be used or molded onnot only at intersection points of a ribbed structure which reinforcesthe plastic structure, but also at the reinforcing ribs between theintersection points, so that a plurality of joining points are formed,at which the plastic structure and the metal body can be connected toone another in a positive and non-positive manner. In addition to thedome surfaces, the plastic structures may, of course, also be connectedto the metal component in a manner in accordance with the invention orin a conventional manner at other joining points.

The plastic ribs of the ribbed structure which reinforces the plasticstructure preferably have, on their upper edge, i.e. in the region ofthe highest loads, a wall which is arranged substantially perpendicularto this ribbed structure and lies flat. This on the one hand reduces themaximum stresses in the loaded plastic and on the other hand preventsthe ribbed structure from bulging or bending under load.

Furthermore, the plastic structure may be designed in such a way that,in addition to the plastic ribs at the upper end of the ribs or domes,it has a closed surface in the manner of a cover, which is provided withapertures or passages only at the upper ends of the domes. In this way,in combination with a U-shaped metal body, a quasi-continuous hollowprofile is formed. In one embodiment, the edge regions of cover andmetal body are also connected to one another in accordance with theinvention or in a conventional way, for example by means of subsequentencapsulation by injection molding.

Furthermore, composite components of sandwich structure can be producedby comprising a plastic structure arranged centrally or in the core andtwo metal sheets which are connected thereto, lie on the outside and arepreferably of flat design. The plastic structure, which serves as aspacer, has the above-described domes in order to form the joiningpoints, some of the domes being open at the top and having a basesurface at the bottom end side and the remainder of the domes being ofprecisely the opposite design, i.e. being open at the bottom andprovided with a base surface which lies at the top. At the locations ofthe plastic structure at which the domes are open, the adjacent metalsheets have apertures, so that the joining tool can penetrate into thedomes and have access to the joining points. The connections betweenplastic structure and metal sheet are produced in the base of the domesin a similar manner to the procedure described above.

The invention is explained in more detail below with reference to thedrawing, in which:

FIG. 1 shows a metal base body and the plastic structure in the regionof the connecting point prior to joining,

FIG. 2 shows a metal base body and the plastic structure in the regionof the connecting point after the joining in a positive and non-positiveconnection through widening of the elevation, which is configured in themanner of a stamped collar, in its center and narrowing at the upperend,

FIG. 3 shows a metal base body and the plastic structure in the regionof the connecting point after the joining with positive and non-positiveconnection by narrowing of the stamped collar in the center and wideningthereof at the upper end,

FIG. 4 shows part of the upper half of the joining tool with a specialencircling annular groove, in an enlarged view,

FIG. 5 shows a metal base body and the plastic structure in the regionof the connecting point after the joining with positive and non-positiveconnection by widening of the stamped-collar-like elevation, whichprojects out of the plastic structure, at its upper end,

FIGS. 6 and 6.1 show a dome-like elevation in perspective view and incross section,

FIGS. 7 and 7.1 show a U-shaped metal body with injection-molded, ribbedplastic insert with dome-shaped elevations at the intersection points ofthe ribbed structure,

FIGS. 8 and 8.1 show a U-shaped metal body with injection-molded, ribbedplastic insert and dome-shaped elevations in the center between theintersection points of the ribbed structure,

FIGS. 9 and 9.1 show a U-shaped metal body with ribbed, injection-moldedplastic insert, which is designed as a cover and, after the joining,together with the metal body forms a closed hollow profiled section, and

FIGS. 10 and 10.1 show a composite body of sandwich structure,comprising an upper metal sheet and a lower metal sheet and aninjection-molded plastic structure which is provided with side walls anddome-shaped elevations.

The illustration shown in FIG. 1 illustrates a metal base body and theplastic structure in the region of the connection point prior to thejoining operation.

The illustration shown in FIG. 1 represents the press tools of a toolwhich carries out the joining operation in the moved-apart position. Thetwo joining tools which lie opposite one another, namely the upperjoining tool 11 and the lower joining tool 13, have contact surfaces 12and 14, respectively, which face one another. The two parts of thecomposite component which are to be joined to one another, namely theplastic structure 1 and the metallic component 4, are situated betweenthe moved-apart contact surfaces 12 and 14 of the upper joining tool 11and the lower joining tool 13, respectively.

In the course of stamping or deep-drawing, the metal body or the metalsheet 4 may be provided with apertures 6 which are, for example, ofcircular configuration. The apertures 6 of circular configuration arepreferably designed in the diameter range of from 2 to 12 mm in themetallic component 4; said processes can be used to produce them. Duringthe stamping or deep-drawing, elevations 7 which run in the form ofstamped collars and finish in a sharp peripheral edge 8 at the upper endof the aperture are formed laterally on the apertures 6. The aperture 6is produced substantially symmetrically with respect to its line ofsymmetry 10. The peripheral edge 8 which is formed at the upper end 9 ofthe deformed region 7 configured in the manner of a stamped collar ispreferably of angular design, in order to allow the deformation 7 topenetrate at the underside 3 of the plastic structure 1.

To press together sheet-metal base body 4 and plastic structure 1,presses or stamping and/or deep-drawing machines or similarhydraulically acting joining machines which are suitable forsheet-metalworking or sheet-metal deformation can be used. They aregenerally equipped with one or more tools 11 and 13 which are accuratelymatched to the contour of the components 1 and 4 which are to beconnected to one another. For optimum introduction of the joining forceduring assembly of said component, it is necessary for both the metallicbase body 4, on the one hand, and the plastic structure 1 arrangedopposite it, on the other hand, to bear accurately against thecorresponding tool contact surface 12 or 14, respectively, at theconnecting points, i.e. the joining points, or in their immediatevicinity.

In general, any metal or any metal alloy can be used for the metalcomponent, provided that, in the solid state, it is hard enough to bestamped into the plastic structure. It is customary to use a metalcomponent made from ungalvanized or galvanized steel, aluminum ormagnesium. To protect against corrosion or for visual reasons, the metalcomponent may also be covered with a commercially available coatinglayer. Corrosion-resistant or color coatings of this type and theirapplication are known to the person skilled in the art.

Injection-molded or thermoformed moldings, including films andsemifinished products (panels, tubes, sheets, bars, etc.) are suitablefor use as plastic structures. The plastic structures are usuallycomposed of thermoplastic, partially crystalline or amorphous polymers,but may also be formed from thermosets or mixtures of these polymergrades.

Suitable thermoplastic polymers are all thermoplastics which are knownto the person skilled in the art. Suitable thermoplastic polymers aredescribed, for example, in Kunststoff-Taschenbuch [Plastics Manual], Ed.Saechtling, 25^(th) Edition, Hanser-Verlag, Munich, 1992, in particularChapter 4 and references cited therein, and in Kunststoff-Handbuch[Plastics Handbook], Ed. G. Becker and D. Braun, Volumes 1–11,Hanser-Verlag, 1966–1996.

Examples of suitable thermoplastics which may be mentioned includepolyoxyalkylenes, such as polyoxymethylene, e.g. Ultraform® (BASF AG),polycarbonates (PC), polyesters, such as polybutylene terephthalate(PBT), e.g. Ultradur® (BASF AG), or polyethylene terephthalate (PET),polyolefins, such as polyethylene (PE) or polypropylene (PP),poly(meth)acrylates, e.g. PMMA, polyamide, such as polyamide-6 orpolyamide-66, (e.g. Ultramid®; BASF AG) vinylaromatic (co)polymers, suchas polystyrene, syndiotactic polystyrene, impact-modified polystyrene,such as HIPS, or ASA (e.g. Luran® S; BASF AG), ABS (e.g. Terluran®; BASFAG), SAN (e.g. Luran®; BASF AG), or AES polymers, polyarylene ethers,such as polyphenylene ether (PPE), polyphenylenesulfides, polysulfones,polyethersulfones, polyurethanes, polylactides, halogen-containingpolymers, imide-containing polymers, cellulose esters, silicone polymersand thermoplastic elastomers. It is also possible for mixtures ofdifferent thermoplastics to be used as materials for the plasticstructures. These mixtures may be single-phase or multiphase polymerblends.

Furthermore, the plastic structures may contain customary additives andprocessing aids.

Examples of suitable additives and processing aids are lubricants ormold-release agents, rubbers, antioxidants, stabilizers to counter theaction of light, antistats, flame retardants, fibrous and pulverulentfillers, fibrous and pulverulent reinforcing agents and other additives,or mixtures of these.

Examples of fibrous and/or pulverulent fillers and reinforcing agentsare carbon fibers or glass fibers in the form of glass fabrics, glassmats or glass-fiber rovings, shot glass or glass beads. Glass fibers areparticularly preferred. The glass fibers used may be made from E, A or Cglass and are preferably provided with a size, e.g. based on epoxyresin, silane, aminosilane or polyurethane, and a coupling agent basedon functionalized silanes. The glass fibers may be incorporated eitherin the form of short glass fibers or in the form of continuous strands(rovings).

Suitable particulate fillers are, for example, carbon black, graphite,amorphous silica, whiskers, alumina fibers, magnesium carbonate (chalk),powdered quartz, mica, bentonite, talc, feldspar or in particularcalcium silicates, such as wollastonite, and kaolin.

Furthermore, the plastic structures may also contain colors or pigments.

The abovementioned additives, processing aids and/or colors arepreferably mixed in an extruder or other mixing device at temperaturesof 100 to 320° C., so that the thermoplastic polymer is melted, anddischarged. The use of an extruder is particularly preferred, inparticular of a corotating, closely intermeshing twin-screw extruder.Processes for producing the plastic molding compounds are well known tothe person skilled in the art.

The molding compounds produced in this way can be used to produce allkinds of plastic structures (including semi-finished products), forexample using the injection-molding or thermoforming process.

Furthermore, the illustration shown in FIG. 1 shows the wall thickness1.1 of the plastic structure 1 between upper side 2 and lower side 3 inmore detail, as well as the height of the elevations 7, which aredesigned in the manner of stamped collars, on the metallic base body 4.Preferred values for the wall thickness 1.1 of the plastic body arebetween 2 and 8 mm. The height of the edges, which have been deformed inthe manner of stamped collars, of the apertures 6, which is denoted by7.1, exceeds the plastic wall thickness 1.1 in the starting state, i.e.in the undeformed state, preferably by approximately 10–30%. Thepercentage may vary according to the particular embodiment.

FIG. 2 shows a metal base body and the plastic structure in the regionof the connection point after the joining in positive and non-positiveconnection by widening of the stamp-collar-like elevation in its centerand narrowing of the stamp-collar-like elevation at the upper end.

The above-described excess height of the edge regions 7 of the aperture6 in the metallic component 4 means that the peripheral edge 8, which isof angular design, of the limit of the apertures 6 penetrates into theplastic structure 1 at the underside 3 and, toward the end of the phaseof penetrating through the plastic wall 1.1, is subjected to theincreased resistance from the oppositely arranged contact surface 12 ofthe upper joining tool, and is consequently deformed. Depending on thesetting angle or length of the excess height 7.1 with respect to thewall thickness 1.1, it is possible for a curvature 17 of the edge region7 of the aperture 6 to be established with a widened section 18 lying inthe center and a narrowed section in the upper region 19 can beestablished. As a result of the deformed contour 17, thestamped-collar-like elevation 7 twists or digs into the plastic wall 1,resulting in a permanent, positive and non-positive connection. Thedesign of the stamped-collar-like elevation 7, which has been deformedby the joining operation, can be influenced firstly by the setting angleof the undeformed protuberance 7 and secondly by the configuration ofthe upper joining tool 11. Depending on the setting angle of theprotuberance or the deformation 7 in its center, they are either widened18 or narrowed 21 (cf. FIG. 3).

The illustration in FIG. 3 shows a metal base body and the plasticstructure in the region of the connection point after the joining withpositive and non-positive connection by narrowing of thestamped-collar-like elevation in its center and widening thereof at theupper end.

In this configuration, the stamped-collar-like elevation 7 in the metalbase body 4 has experienced a geometry which is opposite to thedeformation contour 17 shown in FIG. 2. In this example too, the height7.1 of the stamped-collar-like elevation 7 which projects beyond thewall thickness 1.1 of the plastic structure 1 means that, after thecontact surface 12 of the upper joining tool 11 comes into contact,digging in or complete penetration and therefore a positive connectionbetween plastic structure 1 and metallic body 4 are achieved.

The extent of the widening or narrowing of the stamped-collar-likeelevation 7 in accordance with FIGS. 2 and 3 is determined by the sizeof the difference between the height 7.1 of the stamped-collar-likeedges and the wall thickness 1.1 of the plastic wall. Therefore, afurther parameter is available for influencing the strength of theconnection.

The illustration shown in FIG. 4 shows part of the upper half of thejoining tool with a specially configured contact surface 12 in moredetail. According to this exemplary embodiment, a recess which issymmetrical with respect to the center axis 10 and is in the form of anannular groove 23 may be formed in the contact surface 12 of the upperjoining tool 11. If a composite component is produced by means of anupper joining tool 11 configured as illustrated in FIG. 4, protuberancesof the metallic stamped collar 7 which project beyond the upper side 2of the plastic structure 1, i.e. do not lie inside this structure, andare deformed and pressed flat by the design of the annular groove 23,are established in the region of the upper side 2 of the plasticcomponent 1 which is designed with wall thickness 1.1.

The illustration shown in FIG. 5 represents a joining tool 11 in moredetail, the contact surface 12 of which is provided, in a correspondingmanner to that illustrated in FIG. 4, with a recess 22 in the form of anannular groove.

When the joining tools 11 and 13, which are arranged opposite oneanother, are pressed together, the elevation 7, which is configured inthe manner of a stamped collar, in the metal body 4 or metal sheet 4penetrates through the plastic component 1, which is designed with wallthickness 1.1, projecting parts of the stamped-collar-like elevation 7engaging in the annular groove 22, which is illustrated in FIG. 4, inthe contact surface 12 of the upper joining tool 11. It can be seen fromthe illustration in FIG. 5 that the elevations 7, which are configuredin the manner of stamped collars, of the metal sheet or the metal body4, in the center of the aperture 6, have undergone a central narrowing,while in the upper region the projecting parts 23 of thestamped-collar-like elevation 7 are formed further apart, in accordancewith the geometry of the annular groove 22 in the contact surface 12 ofthe upper joining tool 11. The accuracy of the joining operation shownin FIG. 5 is improved by the fact that both the metal sheet or the metalbody 4 is supported without play on the corresponding contact surface 14of the lower joining tool 16 and with uniform support in the vicinity ofthe joining point. The same also applies to the arrangement of theplastic component 1, which is arranged above the metal body or metalsheet 4, with respect to the contact surface 12 of the upper joiningtool 11.

FIG. 6 shows a dome-shaped elevation of the injection-molded plasticstructure in a perspective view and in cross section.

According to the illustration shown in FIG. 6, a dome-shaped elevation30 is formed at the intersection point 27 of a plastic structure 25which is provided with a ribbed structure 29. This elevation 30 isprovided with an open end 30.1, into which the joining tool moves. Atthe end which faces the shell-like metal body 24, the dome-likeelevation 30 is provided with a base surface 30.2. The wall thickness ofthe dome-like elevation, at the base 30.2 of which a joining point 34 isproduced, is denoted by reference numeral 30.3.

It can be seen from the cross-sectional illustration of the dome-likeelevation 30 shown in FIG. 6 that its base surface 30.2 has the end 9 ofthe stamped-collar-like elevation 7 penetrating through it, so that ajoining point 34 is formed at the base surface 30.2 of the dome-shapedelevation 30, at which joining point 34 the metal body 4, which rests onthe contact surface 14 of the lower joining tool 13, is positivelyconnected to the plastic structure 1. The mating force which is requiredfor a positive connection is applied by a ram which moves into theopening in the dome-like elevation 30.

The illustration shown in FIG. 6.1 represents a plastic structure 1which is designed with a wall thickness 1.1. Passing through it is anend 9 of a stamped-collar-like elevation 7 which is formed symmetricallywith respect to a center axis 10, on the metal body 4. The height of thestamped-collar-like elevation 7 is less than the wall thickness 1.1 ofthe plastic structure, so that the collar end 9 does not emerge from theopposite side from the metal body 4.

The illustration shown in FIGS. 7 and 7.1 illustrates a metal body whichis configured in the form of a shell and is provided with aninjection-molded, reinforcing plastic insert which contains dome-shapedelevations at the intersection points of the ribbed structure.

In accordance with the illustration shown in FIG. 7, the insert plasticbody 25, which serves to reinforce the metal structure 24 which is ofshell-like configuration, has individual dome-shaped elevations 30,which run in the vertical direction, passing through it. The dome-shapedelevations 30 are substantially in the form of hollow cylinders which atthe top have an opening 30.1 for the introduction of a joining tool,i.e. for example, a ram, and at their opposite end, which faces themetallic body 4, are provided with a base surface 30.2. During joining,the base surfaces 30.2 are available for forming the connections 34(joining points) as shown in FIGS. 1 to 6. The wall thickness 30.3 ofthe hollow cylinders, which are provided as dome-like elevations 30,preferably lies in the region of the wall thickness of the plasticstructure 1 or 24. On its side, the plastic body 25 is provided withbearing tongues 26, and at the intersection points 27 of theinjection-molded plastic body 25 reinforcing ribs intersect one another.A ribbed structure 29, which likewise runs in the vertical direction,i.e. parallel to the dome-like elevations 30, of the injection-moldedplastic body 25 imparts to this body firstly, in partial regions, abearing surface against the bottom of the metal body 24, which is ofshell-like configuration, and secondly an additional mechanicalreinforcement. In the region where the bearing tongues 26 bear againstthe wall of the shell-like metal body, which is of U-shapedconfiguration, a joining region 28 is formed, by a joining connectionwhich is formed as shown in FIGS. 1–6 and can be produced bycold-forming processes. Components which have been joined in this waycan also be referred to as having been hooked together. If this takesplace at a plurality of locations simultaneously (cf. FIG. 7.1), at allthe joining regions denoted by reference numerals 28 and 34, thecomposite component which has been formed and joined in this wayinherently has an enormous rigidity and a high level of precision withregard to the dimensions of the two components which are to be fixedtogether.

In its upper region, each of the plastic ribs of the plastic structure24 is provided with reinforcing surfaces 16 in the region at which it ishighly loaded. The reinforcing surfaces 16 are additionally molded-onwalls which are arranged perpendicular to the ribbed structure 29. Theyfirstly prevent the occurrence of unacceptably high maximum stresses inthe loaded plastic body and secondly counteract the bulging and bendingof the ribbed structure 29. To take into account the principle oflightweight construction, the plastic ribs are withdrawn or hollowed outin the regions 29.1 which face the bottom and the corners of theU-shaped metal sheet. This manner of designing the plastic ribbedstructure follows the principle of arranging material where highstresses occur under load and omitting material where the stresses whichoccur are low.

The illustration shown in FIGS. 8 and 8.1 shows a U-shaped metal bodywith a ribbed plastic insert, individual dome-shaped elevations, whichare preferably designed as hollow cylinders, being provided in thecenter, between the rib intersection points. Unlike the injection-moldedplastic structure 25 illustrated in FIGS. 7 and 7.1, in accordance withthe illustrations in FIGS. 8 and 8.1, the dome-shaped elevations 30 arearranged on the injection-molded plastic structure 25 not at theintersection points 27 of the plastic structure 25, but rather along thecourse of the diagonally running ribs, in each case in the regionbetween two intersection points, whether in the center of the plasticstructure 25 or at an intersection point on the wall of the plasticstructure 25. According to this design variant of the plastic structuretoo, the ribbed structures 29 are provided on their upper side withreinforcing surfaces 16 which effectively prevent bulging or bending ofthe ribbed structure 29 of the plastic structure 25 when load isimposed. The design variant of the plastic structure shown in FIGS. 8and 8.1 can be used to form a plurality of joining points 34 in plasticstructure 25 and metal body 24, which is of dish-like configuration, sothat the strength of a hybrid component produced in this way can beincreased considerably. In the exemplary embodiment illustrated in FIGS.7 and 7.1 of an injection-molded reinforcing plastic insert in a metalprofiled section which is of dish-like configuration, dome-likeelevations 30 can be formed at the intersection points of the ribbedstructure 29, centrally with respect to the metal body 24 which is ofdish-like configuration.

In the plastic structures 25 shown in FIGS. 8 and 8.1, bearing tongues26 are once again molded on in the region of the bearing contact. Theyrest on the side faces, which are of U-shaped profile, of the dish-likemetallic body 24 and are joined to this body by cold-forming processesin accordance with the process outlined above.

The illustration in FIGS. 9 and 9.1 shows a U-shaped metal body withribbed plastic insert, which, expressed in simplified form, is designedas a cover and, after it has been joined to the metal body, forms aclosed hollow profiled section. Profiled sections of this type have ahigh torsional rigidity.

According to this design variant, a shell-like metal body 24 and aplastic sheet structure 31, which is ribbed on the reverse side, areconnected to one another. A cross-rib structure 29 is provided on therear side of the cover surface 31.1, for the purpose of reinforcing thecover surface 31.1. Hollow cylinders which are open at the top, have abase surface 30.2, function as spacers and dome-like elevations and facetoward the deep-drawn side of the shell-like metal body 24 are formed inthe intersection points of the individual ribs 29. The above-describedapertures with the elevations 7 (FIGS. 1–6), which are configured in themanner of stamped collars and are not shown in the illustration given inFIG. 9, are situated in the shell-like metal body 24. When they arepressed together, i.e. when a joining tool is introduced into thehollow-cylindrical spacers or dome-like elevations 30, 33 and the metalbody, which is of shell-like configuration, is pressed on, a joiningpoint 34 to the metal body 24, which is of shell-like configuration, asshown in FIGS. 1–6 is formed in the base surface 30.2 of each dome-likeelevation or spacer 30 or 33 as illustrated in FIG. 9.

It can be seen from the illustration in FIG. 9 that the ribbed plasticsheet structure 31 is provided on its upper side, in the region of thedome-shaped elevations 30 or spacers 33, with openings 30.1 into which ajoining tool moves. The joining tool, which passes through the hollowcylinders of the dome-shaped elevations 30 or spacers 33 until itreaches their base surface 30.2, applies the joining forces which arerequired to join the shell-like metal body 24 to the ribbed sheetstructure 31. Consequently, there is a digging-in effect, i.e. apermanent, positive connection between the ribbed sheet structure 31 inthe region of the base surface 30.2 and the bottom of the metallic basebody 24 and by means of further joining points 34 along the contactregions 32 between the angled-off limbs of the shell-like base body 24and those regions of the ribbed sheet structure 31 which cover them.

The assembly drawing 9.1 shows the joined composite component in moredetail, comprising a ribbed, sheet-like plastic structure 31 and theshell-like metal profiled section 24 which is profiled in a U shape. Thebase surface 30.2, which rests on the bottom of the shell-like metalprofile, of the hollow-cylindrical, dome-like elevations 30 or spacers33 forms the joining point 34 which is adjoined by the cylindricalregion, i.e. the spacer 33 between ribbed sheet structure 31 andshell-like metal body 24.

The illustration shown in FIGS. 10 and 10.1 shows a design variant of acomposite component which corresponds to a sandwich structure. Profiledsections of this type have a high flexural strength.

The parts, illustrated in FIG. 10, of the composite component, which isshown in its joined state in FIG. 10.1, comprise in each case ametallic, large-area body 35 and 40 on the top and bottom sides,respectively. The metallic, large-area bodies 35 and 40 are providedwith openings in the region at which they rest on the openings 30.1 ofdome-shaped elevations 30 of the plastic structure 37, so that thejoining tool is able to move into the hollow-cylindrical, dome-shapedelevations 30 of the plastic structure 37. The metallic large-areabodies 35 and 40, which function as cover and base, respectively, of acomposite component, are provided with recesses 42 in the region of theopenings 44 in the side walls 43 of the injection-molded component 37.In the top side 35 and the bottom side 40 of the metallic surfaces, therecesses 42 are designed in such a way that in each case access to themutually opposite recesses 44 in the side walls 43 of theinjection-molded plastic component 37 are open at the top side.

It can be seen from the illustration in FIG. 10.1 that the individualrecesses 44, which lie next to one another, in the side walls 43 of theinjection-molded component 37 are accessible in accordance with FIG. 10either from the top side or from the bottom side of the compositecomponent in accordance with FIG. 10.1.

In addition to the height of the side walls 43, the distance between theupper metallic surface 35 and the lower metallic surface 40 on thecomposite component shown in FIG. 10.1 is defined by dome-shapedelevations 30 designed centrally on the injection-molded component 37.When the metal sheets 35, 40 and the plastic structure 37 are beingjoined together, the above-described connections in accordance withFIGS. 1–6, by means of which the basic rigidity and strength of thecomposite component are achieved, are formed at the joining points 34.

The metallic base body 4 provides the composite component designed inaccordance with the different design variants with the basic strengthand rigidity. The plastic structure, which may be provided in accordancewith the design variants which form the basis of the above examples,serve firstly to further increase the rigidity and strength and secondlyto integrate functions with a view to forming systems or modules.

There are numerous possible applications for the composite componentsdescribed, for example as components or component parts in theautomotive industry, in aircraft construction or in shipbuilding or forthe production of domestic or electrical appliances, known as white orbrown goods. Examples of applications in the automotive industry includefront end modules, front end supports, seat pans, seat structures,instrument panels, functional supports for doors, functional modules fordoors, tailgates or side doors. Suitable examples for domestic andelectrical appliances include supporting frames for photocopiers,television sets, washing machines or dishwashers, refrigerators andsewing machines.

Compared to the known hybrid components which are produced in adifferent way, as described in EP 0 370 342 B1, the proposed compositecomponents have the advantage that the plastic structure can in thiscase be designed substantially without restriction, since according tothe present invention the plastic structure can be manufactured in aseparate production step. By contrast, the plastic structure inaccordance with EP 0 370 342 B1 is injection-molded onto the metallic,shell-like base body, and consequently the degrees of freedom in termsof the demolding of the injection-molded plastic structure areconsiderably reduced. Consequently, the plastic structure according tothe invention can be designed so as to be better able to bear the loadsthan those from the prior art. In the composite component obtained, thisadvantage manifests itself by a higher rigidity or strength combinedwith a similar component weight.

A further advantage is that, since there are no additional processingsteps, e.g. adhesive bonding steps, short cycle times can be achieved inseries production. Furthermore, there is no need for any additionalcomponents or parts for joining plastic structure and metal component.Moreover, the process according to the invention is overall lesssusceptible to deviations during the positioning of stamped edge andplastic structure. In the process described in EP 0 370 342 B1, a muchgreater positional accuracy has to be maintained if functioningcomposite components are to be achieved. Also, the joining processaccording to the invention does not require any further treatment.Furthermore, any desired plastic structures, irrespective of theirproduction process, can be used; fiber-reinforced plastics are equallysuitable. For example, in a shearing test with a composite componenthaving a plastic structure made from glass-fiber-reinforced (30% byweight) polyamide with circular stamped edges with a diameter of 5 mm inthe metal component, the fracture forces for each connection point areapproximately 1300 N.

LIST OF REFERENCE SYMBOLS

-   1 Plastic structure-   1.1 Wall thickness-   2 Top side-   3 Lower side-   4 Metal body/metal sheet-   5 Joining point-   6 Aperture-   7 Stamp-collar-like elevation-   7.1 Height of the protuberance-   8 Peripheral edge-   9 Collar end-   10 Center axis-   11 Upper joining tool-   12 Contact surface-   13 Lower joining tool-   14 Contact surface-   15 Deformed collar region-   16 Reinforcing surface-   17 Curvature-   18 Central widening-   19 Upper narrowing-   20 Upper widening-   21 Central narrowing-   22 Recess in upper joining tool 11-   23 Projecting part-   24 Shell-like metal body-   25 Plastic body-   26 Bearing tongues-   27 Intersection point-   28 Joining region-   29 Ribbed structure-   29.1 Recess or cutout-   30 Dome-like elevation-   30.1 Opening-   30.2 Base surface-   30.3 Wall thickness-   31 Ribbed sheet structure-   31.1 Cover surface-   32 Shell-like metal body bearing-   33 Spacer-   34 Joining point-   35 Metal plate, upper-   36 Apertures-   37 Plastic structure-   38 Grid structure-   39 Opening in metal body-   40 Metal plate, lower-   41 Rib-   42 Recess-   43 Side wall-   44 Oppositely running recess

1. A process for producing a composite component from a metal component(4, 24, 35, 40) and a plastic structure (1, 25, 31, 37), which comprisesproviding a metal component (4, 24, 35, 40) which has at least onesurface with at least one protuberant stamped edge, and providing theplastic structure (1, 25, 31, 37), placing the metal component and theplastic structure into joining tools (11, 13) such that the protuberantstamped edge of the metal component faces a surface of the plasticstructure, and bringing the joining tools together such that theprotuberant stamped edge of the metal component penetrates into theplastic structure and is deformed therein in a positively andnon-positively locking manner, and wherein the stamp edge forms astamped collar of an aperture passing through the metal surface of themetal component.
 2. A process as claimed in claim 1, wherein the stampededge is arranged substantially vertically on the metal surface.
 3. Aprocess as claimed in claim 1, wherein the end of the stamped edge isangular in form.
 4. A process as claimed in claim 1, wherein the heightof the stamped edge exceeds the thickness of the plastic structure atthe point which is to be joined.
 5. A process as claimed in claim 1,wherein the height of the stamped edge exceeds the thickness of theplastic structure at the point which is to be joined by up to 40percent.
 6. A process as claimed in claim 1, wherein the height of thestamped edge exceeds the thickness of the plastic structure at the pointwhich is to be joined by up to 35 percent.
 7. A process as claimed inclaim 1, wherein the metal component (4, 24, 35, 40) and the plasticstructure (1, 25, 31, 37) are joined at a joining point (5) having adeformation contour (19, 20, 21, 22) which is influenced by theconfiguration of the contact surface (12, 22) of the upper joining tool(11).
 8. A process as claimed in claim 1, wherein the height (7.1) ofthe elevation or stamped edge (7) is less than the wall thickness (1.1)of the plastic structure (1, 25, 31, 37) or is equal to the wallthickness (1.1) of the plastic structure.
 9. A process as claimed inclaim 1, wherein the metal component is in the shape of a shell.
 10. Aprocess as claimed in claim 1, wherein the plastic structure (1, 25, 31,37) comprises at least one dome-shaped elevation (30) which is open atthe top and has a base surface (30.2) facing the metal component (4, 24,35, 40), and wherein the base surface of the dome-shaped elevation formsthe surface of the plastic structure which faces the protuberant stampededges of the metal component.
 11. A process as claimed in claim 10,wherein the plastic structure (1, 25, 31, 37) comprises at least twodome-shaped elevations (30) which are connected to one another by areinforcing ribbed structure (29).
 12. A process as claimed in claim 1,wherein the plastic structure (1, 25, 31, 37) comprises a reinforcing,self-intersecting ribbed structure (29), at least one intersection point(27) being designed as a dome-shaped elevation (30) which is open at thetop and has a base surface (30.2) which faces the metal body (4, 24, 35,40).
 13. A process as claimed in claim 1, wherein the plastic structure(1, 25, 31, 37) comprises a reinforcing ribbed structure (29) whichintersects itself at least once and the ribs of which, between theintersection points (27), have open, dome-shaped elevations (30) with abase surface (30.2) which faces the metal body (4, 24, 35, 40).
 14. Aprocess as claimed in claim 1, wherein the ribbed structure (29) of theplastic structure has recesses or cut-outs (29.1) which are adapted toprovide a lightweight construction and to prevent losses of rigidity andstrength.
 15. A process as claimed in claim 11, wherein the plasticstructure (1, 25, 31, 37) is provided with reinforcing surfaces (16)which run substantially perpendicular to the ribbed structure (29). 16.A process as claimed in claim 15, wherein the surfaces (16) which runsubstantially perpendicular to the ribbed structure form a continuouscover surface (31.1).
 17. A process for producing a sandwich component,wherein metal components (35, 40), which are provided as top side andunderside of the sandwich component and each of which have at least onesurface with at least one stamped edge and stamped-out portions (42),are placed into two opposite halves of a joining tool, a plasticstructure (1, 25, 31, 37), which comprises dome-shaped elevations (30)which have top and the base surfaces with openings (30.2) whichalternately bear against the metal components (35, 40) and the openingsof which correspond to the stamped-out portions of the metal componentsbearing against them, is positioned between the metal components, andthe joining tools are brought together, the corresponding stamped edgebeing pressed in a positively and non-positively locking manner into theplastic structure.
 18. A process as claimed in claim 17, wherein spacers(33) are provided on the plastic structure (37).